MCB Tripping

I have a 5.2 kWh Secondary with a 9.5 kWh Primary battery set up on a 5 kW Hybrid system. Both batteries are now on firmware 3015.

All of a sudden, the MCB between the secondary and primary batteries is tripping when charging in the overnight period. The primary has the built in MCB and that is fine. This does seem to be happening since the move to 3015, but I can't narrow it down to just that. It doesn't happen on a daily basis, but once or twice a week. Could it be a dodgy MCB? Would a large difference in SoC between the batteries cause an issue like that when charging? Supports usual response is to just get the installer out to look at it but they aren't answering their phone.

Some installers are rubbish and do not seem to want to know when they have finished the install.

I can't see why it should be the battery firmware update that is causing it to trip now. Although the batteries will and their BMS will limit the charge when getting to full it is the inverter that provides the 3600 charging watts.

It is always tempting to think an MCB is faulty when it starts tripping it may be some kind of fault more likely that has just surfaced I would say based on MCBs trip for a reason.

It is best to get it checked.

I recently had a similar issue. I have two 8.2 kW GE batteries, daisychained to an AC3 coupled inverter. There is a DCMCB between inverter and primary battery that was tripping. I contacted GE twice (at the time, I didn't realise that the breaker was tripping). GE diagnosed the problem and suggested that I contact my installer, which I did. My installer couldn't give me a date for a visit for 10 days. When they arrived, they replaced the DCMCB (a 30 min job) and the new breaker has behaved itself. My installer told me that they had replaced this breaker previously.
Worth viewing this youtube video which mirrors my problem:
https://www.youtube.com/watch?v=XsIi3aZ7cJw&t=2s
At least you have your master battery working. I hobbled through the 10 days by reducing charge and discharge rates by 50%. But not good in the middle of the recent cold spell when I want to grab any cheaper electricity slots and make the most of saving sessions.
So get on to your installer first thing on Monday!

Rob

Cheers. I'll keep trying the installer.